Methods and apparatus for marking orthodontic products are discussed below with reference to the marking of an orthodontic band, for example, that can be attached to teeth to straighten them. The band 5, shown in FIG. 3, is in the form of a ring that is modeled on a tooth.
Human teeth differ in shape depending on whether they are in the upper or lower jaw and whether they are on the right or left side. Also, the size of teeth varies from individual to individual. Because of the differences in tooth size and shape, it is necessary to use different orthodontic bands to match the teeth on which the bands are to be used. To enable orthodontic treatment to be performed properly and efficiently, it is therefore important that the bands be clearly marked with characters indicating whether the bands may be used on the upper or lower jaw and the right or left side along with characters indicating the size of the bands. Proper marking also prevents different bands from becoming mixed together when shipped from the factory.
Prior methods and apparatus for marking orthodontic products have failed to consider the effects of sterilization processes used to prevent infection with viruses like B-type hepatitis viruses and HIV viruses. The markings made on orthodontic products by the prior art is sometimes removed during sterilization by the rigorous heating conditions involved or by immersion of the products in disinfectants.
The size of orthodontic product such as an orthodontic band to be used on a patient is determined by trial of different sized products on the patient's teeth. As a result of the trials, the products are regularly contaminated with saliva and require frequent and repeated sterilization.
Prior methods of marking orthodontic products include printing characters on the products with ink and engraving characters on the products with laser beams. Markings made by printing tend to peel off when the orthodontic product is heated and when hydrochloric acid type disinfectants are applied to the product during sterilization. Characters produced by lasers are often thin and unreadable. In addition, marking with lasers is time consuming and requires substantial equipment.
It is difficult to accurately control the depth of the marking when markings are made using lasers. Moreover, with the use of lasers, band strength tends to decrease and the band becomes blunt from the heat generated by the process.